Process for producing a cationic polyurethane

Abstract

Cationic polyurethanes and a process for their production wherein a polyisocyanate, preferably a diisocyanate such as 2,4- or 2,6-tolylene-diisocyanate is reacted with an aliphatic dihydroxy compound substituted with an aliphatic side-chain of at least 10 carbon atoms to form a preliminary adduct or so-called prepolymer with terminal - NCO groups. This prepolymer is then reacted for chain-lengthening with an aliphatic monomeric diol (A) containing a tertiary nitrogen atom convertible into an ammonium compound or an aliphatic monomeric diol (B) containing a tertiary nitrogen atom already converted into an ammonium compound. The new cationic polyurethanes are especially useful as sizing agents for the sizing of paper.

The invention is hereby claimed as follows: 
     
       1. A process for the production of a cationic polyurethane which comprises: converting a monomeric aliphatic dihydroxy compound substituted with an aliphatic side-chain of at least 10 carbon atoms, by reaction with a polyisocyanate into a preliminary adduct with terminal --NCO groups; and   chain-lengthening said adduct by reacting the terminal --NCO groups with A. an aliphatic monomeric diol containing a tertiary nitrogen atom which is subsequently converted into the corresponding ammonium compound, or   B. an aliphatic monomeric diol containing a tertiary nitrogen atom previously converted into the corresponding ammonium compound.     
     
     
       2. A process as claimed in claim 1 wherein said aliphatic side-chain substituent of the dihydroxy compound contains at least 16 carbon atoms. 
     
     
       3. A process as claimed in claim 1 wherein said monomeric aliphatic dihydroxy compound is a glycerol fatty acid monoester. 
     
     
       4. A process as claimed in claim 3 wherein said monoester is glycerol monostearate. 
     
     
       5. A process as claimed in claim 3 wherein said monoester is the behenic acid monoester of glycerol. 
     
     
       6. A process as claimed in claim 1 wherein the monomeric aliphatic dihydroxy compound is one in which the two hydroxy groups are connected by an aliphatic chain of not more than 7 atoms. 
     
     
       7. A process as claimed in claim 6 wherein said aliphatic chain as from 2 to 7 atoms and is selected from the group consisting of alkylene and dialkyleneamine with the side-chain being alkyl connected to a carbon atom of said alkylene or to the nitrogen atom of said dialkyleneamine. 
     
     
       8. A process as claimed in claim 1 wherein said monomeric aliphatic dihydroxy compound is N-stearyl-diethanolamine. 
     
     
       9. A process as claimed in claim 1 wherein said monomeric aliphatic dihydroxy compound is 1,2- or 1,4-dihydroxyoctadecane. 
     
     
       10. A process as claimed in claim 1 wherein hydrogen chloride is used to form the ammonium compound. 
     
     
       11. A process as claimed in claim 1 wherein said aliphatic monomeric diol containing a tertiary nitrogen atom is N-methyl-diethanolamine. 
     
     
       12. A process as claimed in claim 1 wherein said aliphatic monomeric diol containing a tertiary nitrogen atom is 1,2-propanediol-3-dimethylamine. 
     
     
       13. A process as claimed in claim 1 wherein the cationic polyurethane is produced in acetone as a solvent. 
     
     
       14. A process as claimed in claim 1 wherein the chain-lengthened product obtained with the diol (A) is first dried before being converted into said ammonium compound. 
     
     
       15. The cationic polyurethane product obtained by the process of claim 1. 
     
     
       16. A cationic polyurethane consisting essentially of the structural units of the formula   ABAD     in which:     A is CO-NH-R-NH-CO,     R being the hydrocarbon radical of a diisocyanate; B is a member selected from the group consisting of ##EQU4## n being an integer of from 9 to 21 and m being an integer of from 10 to 22; and   D is a member selected from the group consisting of ##EQU5## R' being lower alkyl of 1 to 4 carbon atoms, r and s each being an integer of 2 to 6 and r + s being not more than 6 and X -  being the anion of an acid.   
     
     
       17. A cationic polyurethane as claimed in claim 16 wherein n is an integer of 15 to 21, m is an integer of 16 to 22, and r and s each denotes an integer of 2 to 3. 
     
     
       18. A cationic polyurethane as claimed in claim 16 wherein R is 2,4- or 2,6-tolylene. 
     
     
       19. A paper sizing composition in which the essential sizing agent is the cationic polyurethane as claimed in claim 16. 
     
     
       20. A cationic polyurethane as claimed in claim 16 having a molecular weight in the range of about 3,000 to 20,000. 
     
     
       21. A cationic polyurethane as claimed in claim 16 wherein the diisocyanate of the radical R consists essentially of a mixture of toluene-diisocyanate - (2,4) and - (2,6), B is the member ##EQU6## n being 17, D has the same meaning as given in claim 16. 
     
     
       22. A process for making a cationic polyurethane which comprises reacting a monomeric aliphatic dihydroxy compound substitued with an aliphatic side-chain of at least 10 carbon atoms, an organic polyisocyanate and (1) an aliphatic monomeric diol containing a tertiary nitrogen atom and subsequently converting the tertiary nitrogen atom into the corresponding ammonium compound; or (2) an aliphatic monomeric diol which contains a nitrogen atom which has been converted into the corresponding ammonium compound. 
     
     
       23. The process of claim 22 wherein the said substituted monomeric aliphatic dihydroxy compound has 2 to 7 carbon atoms in its main chain, the organic polyisocyanate is a diisocyanate, and the diol (1) or (2) has only one or two tertiary nitrogen atoms or corresponding ammonium compounds which are in the main chain at a point removed from between the hydroxyl groups. 
     
     
       24. A cationic polyurethane prepared by the process of claim 23.